1. Field of the Invention
This invention relates generally to a sheet metal clamp, and particularly to a body sill clamp for use in straightening the sheet metal and frame of a car in any body shop.
2. Description of the Prior Art
A problem arises during the straightening of sheet metal and the frame of conventional automobiles, and the like, requiring body work with regards to obtaining a good grip on the sheet metal or frame element being straightened. This is particularly a problem when gripping sheet metal along an edge thereof, since the metal tends to tear-out or slip from between the gripping elements.
U.S. Pat. No. 3,108,629, issued Oct. 29, 1963, to V. J. Jenkins, discloses a body clamp which employs a plurality of pins to help retain a piece of sheet metal, and the like, in a longitudinal channel provided in a clamping head of the device. Dimples disposed in the channel permit the pins to penetrate the sheet material being clamped, although this one-way penetration has been found unsatisfactory in some instances. U.S. Pat. No. 3,131,747, issued May 5, 1964, to E. J. Junkins, discloses a clamp assemblage in which the clamp jaws are provided with gripping teeth capable of exerting forces in different directions on a piece of sheet metal being gripped by the clamp. This known clamp assemblage, however, employs a pivoted moving jaw that somewhat limits the versatility of the device. Further, special gripping teeth need necessarily be employed with this known clamp assemblage.
A more recent development and the approach which is conventionally employed is shown in U.S. Pat. No. 3,827,279, issued Aug. 6, 1974, to E. Buske. The known wedge-tight clamp shown in this prior patent, however, does away with the penetrating teeth, and substitutes instead some protuberances that actually decrease the amount of clamping area of the jaws of the device.
Thus, while the clamping devices that do not provide for penetration of the metal, and the like, that are being gripped may have greater resistance to wear than devices which provide for penetration of the metal, the devices that merely grip the metal generally do not provide sufficient gripping force to achieve satisfactory results. The clamping devices which penetrate the sheet metal, on the other hand, tend toward high wear, short life, and resulting higher cost that has made them somewhat unpopular.
I am aware of the following additional U.S. Pat. Nos. that may be pertinent to the invention:
949,096 - Feb. 15, 1910 PA1 2,915,277 - Mar. 26, 1940 PA1 3,463,477 - Aug. 26, 1969 PA1 3,463,479 - Aug. 26, 1969